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AES and CHACHA20 Encrypt/Decrypt Text

See more Encryption Examples

Demonstrates the use of the new EncryptSb and DecryptSb methods introduced in Chilkat v9.5.0.67 to encrypt/decrypt the contents of StringBuilder objects.

Note: This example requires Chilkat v9.5.0.67 or greater.

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Local $bSuccess = False

;  This example assumes the Chilkat API to have been previously unlocked.
;  See Global Unlock Sample for sample code.

;  First build a string to be encrypted
$oSb = ObjCreate("Chilkat.StringBuilder")
Local $i = 1
While $i < 10
    $oSb.AppendInt($i)
    $oSb.Append(" the quick brown fox jumped over the lazy dog." & @CRLF)
    $i = $i + 1
Wend

ConsoleWrite($oSb.GetAsString() & @CRLF)

;  The string to be encrypted looks like this:

;  1 the quick brown fox jumped over the lazy dog.
;  2 the quick brown fox jumped over the lazy dog.
;  3 the quick brown fox jumped over the lazy dog.
;  4 the quick brown fox jumped over the lazy dog.
;  5 the quick brown fox jumped over the lazy dog.
;  6 the quick brown fox jumped over the lazy dog.
;  ...

$oCrypt = ObjCreate("Chilkat.Crypt2")

;  Specify the encryption to be used.
;  First we'll do AES-128 CBC
$oCrypt.CryptAlgorithm = "aes"
$oCrypt.CipherMode = "cbc"
$oCrypt.KeyLength = 128

Local $sIvHex = "000102030405060708090A0B0C0D0E0F"
$oCrypt.SetEncodedIV $sIvHex,"hex"

Local $sKeyHex = "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F"
$oCrypt.SetEncodedKey $sKeyHex,"hex"

;  When EncryptSb is called, the contents of the source (sb)
;  remains unmodified.  The encrypted bytes are written into bdEncrypted.
;  If bdEncrypted already contained data, it is replaced with the encrypted bytes.
$oBdEncrypted = ObjCreate("Chilkat.BinData")
$bSuccess = $oCrypt.EncryptSb($oSb,$oBdEncrypted)
If ($bSuccess <> True) Then
    ConsoleWrite($oCrypt.LastErrorText & @CRLF)
    Exit
EndIf

;  Examine the encrypted bytes:
ConsoleWrite($oBdEncrypted.GetEncoded("base64_mime") & @CRLF)

;  Sample encrypted data:

;  0DdNZ22ckMMJBiaKhAu3wUEfh16XW356NIUsDmNs/xwbHe/p1201OmpfzwXwKktkAefu2pckrBgC
;  df+1w8lRo+KAy5n5wlAgMGM/UrsVJsp0BmDPk1vaxKrmrGpSXOVCQs1n2+0atIs5YLiOG+Va3+Mi
;  EQNb4YK7bNMmvt0++irBxTiGnkx/RncfKwgkbBUpl2x7yV13MW6lapDT6Md0DKAMsTXFJYGeIdEf
;  g2uxDDQzI5gUOUHTMrXQ8paD/K76KKB9Jpp/kAM9z8g/d8KUmuphA7KI64d38xsgOmcITlbhlCQ2
;  PDkcU6RRzX0FUTUSMgQukhy0jkLZEjHX9poKJD+iJTOkcQUC3OqR9hKhSrvIgJN4lxdR71MheOoQ
;  2wmvRdq+agTWWh333Vmb6J6yDV79aSpnqEDrA8Ks7Xzciol0gve91+JtVJlJKjWwEzWEU8GxF7Q8
;  eaWI70lsC5nTLGcbqgKu6gzkzHlHyHaE2FAQA/d5I2dvfsAYUQCza0Zdyw8mmTtHhlP2Tfxj1uPv
;  H4Q7BGuKnx3SWT2CnpbX4091w7KzLAztrbFBo/Tf9w8ZpgTK9k1ryfW9/xnk6rW6iQ==

;  Decrypt to restore back to the original:
$oSbOriginal = ObjCreate("Chilkat.StringBuilder")
$bSuccess = $oCrypt.DecryptSb($oBdEncrypted,$oSbOriginal)
If ($bSuccess <> True) Then
    ConsoleWrite($oCrypt.LastErrorText & @CRLF)
    Exit
EndIf

;  Examine the original data:
ConsoleWrite($oSbOriginal.GetAsString() & @CRLF)

;  ----------------------------------------------------------------------------------
;  To do chacha20 encryption, just change the settings:

$oCrypt.CryptAlgorithm = "chacha20"
$oCrypt.KeyLength = 256
;  The initial count is the initial block counter for the chacha20 algorithm.
;  It can be any integer, but must be set to the same when decrypting.
$oCrypt.InitialCount = 22

;  EncryptSb completely replaces the contents of bdEncrypted.
$bSuccess = $oCrypt.EncryptSb($oSb,$oBdEncrypted)

;  However.. DecryptSb appends the decrypted text to whatever may
;  have already existed within sbOriginal.
$bSuccess = $oCrypt.DecryptSb($oBdEncrypted,$oSbOriginal)

ConsoleWrite("----" & @CRLF)
ConsoleWrite("The original data should be here twice.  Once from the AES decrypt, and again from the chacha20 decrypt." & @CRLF)
ConsoleWrite($oSbOriginal.GetAsString() & @CRLF)
ConsoleWrite("Success." & @CRLF)